Pesticidal baits in various forms have been in use for many years. Current insect and other arthropod bait formulas take the form of liquid or syrup baits (for example InTice Thiquid Ant Bait, or Terro pre-filled stations); gels or pastes packaged in syringes or squeeze tubes (for example, InTice Sweet Ant Gel, InTice Roach Bait) or in aerosol or pressurized cans (for example U.S. Pat. Nos. 5,126,139 and 5,021,237); semi-solid wax or oil based baits deployed in ready-to-use stations (for example, Combat roach baits); spreadable pastes packaged in jars; pressed or loose powder baits (for example, Advance Termite Bait, Avert Dry Flowable Cockroach Bait); and granular baits (for example, InTice Granular Bait). Rodent baits take the form of dry pellets, meal, grain, seed, or wax blocks (for example, Contrac rodent baits); or liquids (for example, Liqua-Tox II). Dry granular type rodent baits are often packaged in ready-to-use “place packs” that are placed as such in the control environment. The rodent that encounters the place pack then chews through the package to obtain the bait inside. Prior to that time, the bait is contained and protected. Fat-based paste rodent baits packaged in jars or squeeze or syringe-type tubes are also sold outside the United States (none known in the United States at this time).
Liquid baits have the advantage of being highly attractive to insects due to the moisture content and the ease of consuming the product for the insect. For rodents, liquid baits can be very attractive in facilities with large amounts of alternative food but limited water supply, such as grain storage facilities. Liquid baits have the disadvantage of being spillable, potentially messy to use, and needing generally to be deployed in some sort of container. Indeed, there are numerous patents which address intricate pest station configurations that can be used to minimize spilling of liquid baits (for example, U.S. Pat. Nos. 6,467,216; 7,204,054 and 6,216,384). For ants and other small insects, liquid baits have the further disadvantages that the insect may drown in the bait, or in the case of sticky or syrupy baits, get stuck in the bait, and send out an alarm signal to other insects that might feed. Furthermore, insects can only feed safely around the edges of the liquid bait, which decreases the number of insects that can feed at one time. For successful control, it is best if numerous insects feed at once and the insects then take the bait back to the nest to share.
Squeezable gels and pastes packaged in syringes or other dispensing tubes have the advantage that they can be injected into cracks where pests often harbor. Often they are thick and sticky in texture which allows them to be placed in up and out of the way places. Depending on the specific formulation, they have various disadvantages, namely: they are difficult to remove after treatment, unless placed in a bait station; if they have low moisture content, they are less attractive to pests in certain situations, if they have a high moisture content but can still be squeezed easily out of a tube, they are frequently runny and messy, and don't stay where they are placed; if they are sticky so that they stick easily to the surfaces they are applied to, they are also sticky to insects, and more difficult for insects to ingest; those with relatively high moisture content frequently dry out rather quickly after application and then become less attractive to pests, or may harden to the point that pests cannot ingest them at all.
Semi-solid or solid, oil or wax-based baits deployed in ready-to-use stations are easy to use, but they don't have the moisture content that is highly attractive to pests in certain instances. Similarly, dry baits in powder, granular, pellet, meal, grain, seed, or wax block form, are convenient to use and well-suited to certain control situations, but do not have the moisture content that is highly attractive to pests in certain instances.